drivers/crypto/padlock-aes.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * Support for VIA PadLock hardware crypto engine.
   5  *
   6  * Copyright (c) 2004  Michal Ludvig <michal@logix.cz>
   7  *
   8  */
   9
  10 #include <crypto/algapi.h>
  11 #include <crypto/aes.h>
  12 #include <crypto/padlock.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/types.h>
  16 #include <linux/errno.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/kernel.h>
  19 #include <linux/percpu.h>
  20 #include <linux/smp.h>
  21 #include <linux/slab.h>
  22 #include <asm/cpu_device_id.h>
  23 #include <asm/byteorder.h>
  24 #include <asm/processor.h>
  25 #include <asm/fpu/api.h>
  26
  27 /*
  28  * Number of data blocks actually fetched for each xcrypt insn.
  29  * Processors with prefetch errata will fetch extra blocks.
  30  */
  31 static unsigned int ecb_fetch_blocks = 2;
  32 #define MAX_ECB_FETCH_BLOCKS (8)
  33 #define ecb_fetch_bytes (ecb_fetch_blocks * AES_BLOCK_SIZE)
  34
  35 static unsigned int cbc_fetch_blocks = 1;
  36 #define MAX_CBC_FETCH_BLOCKS (4)
  37 #define cbc_fetch_bytes (cbc_fetch_blocks * AES_BLOCK_SIZE)
  38
  39 /* Control word. */
  40 struct cword {
  41         unsigned int __attribute__ ((__packed__))
  42                 rounds:4,
  43                 algo:3,
  44                 keygen:1,
  45                 interm:1,
  46                 encdec:1,
  47                 ksize:2;
  48 } __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
  49
  50 /* Whenever making any changes to the following
  51  * structure *make sure* you keep E, d_data
  52  * and cword aligned on 16 Bytes boundaries and
  53  * the Hardware can access 16 * 16 bytes of E and d_data
  54  * (only the first 15 * 16 bytes matter but the HW reads
  55  * more).
  56  */
  57 struct aes_ctx {
  58         u32 E[AES_MAX_KEYLENGTH_U32]
  59                 __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
  60         u32 d_data[AES_MAX_KEYLENGTH_U32]
  61                 __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
  62         struct {
  63                 struct cword encrypt;
  64                 struct cword decrypt;
  65         } cword;
  66         u32 *D;
  67 };
  68
  69 static DEFINE_PER_CPU(struct cword *, paes_last_cword);
  70
  71 /* Tells whether the ACE is capable to generate
  72    the extended key for a given key_len. */
  73 static inline int
  74 aes_hw_extkey_available(uint8_t key_len)
  75 {
  76         /* TODO: We should check the actual CPU model/stepping
  77                  as it's possible that the capability will be
  78                  added in the next CPU revisions. */
  79         if (key_len == 16)
  80                 return 1;
  81         return 0;
  82 }
  83
  84 static inline struct aes_ctx *aes_ctx_common(void *ctx)
  85 {
  86         unsigned long addr = (unsigned long)ctx;
  87         unsigned long align = PADLOCK_ALIGNMENT;
  88
  89         if (align <= crypto_tfm_ctx_alignment())
  90                 align = 1;
  91         return (struct aes_ctx *)ALIGN(addr, align);
  92 }
  93
  94 static inline struct aes_ctx *aes_ctx(struct crypto_tfm *tfm)
  95 {
  96         return aes_ctx_common(crypto_tfm_ctx(tfm));
  97 }
  98
  99 static inline struct aes_ctx *blk_aes_ctx(struct crypto_blkcipher *tfm)
 100 {
 101         return aes_ctx_common(crypto_blkcipher_ctx(tfm));
 102 }
 103
 104 static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
 105                        unsigned int key_len)
 106 {
 107         struct aes_ctx *ctx = aes_ctx(tfm);
 108         const __le32 *key = (const __le32 *)in_key;
 109         u32 *flags = &tfm->crt_flags;
 110         struct crypto_aes_ctx gen_aes;
 111         int cpu;
 112
 113         if (key_len % 8) {
 114                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 115                 return -EINVAL;
 116         }
 117
 118         /*
 119          * If the hardware is capable of generating the extended key
 120          * itself we must supply the plain key for both encryption
 121          * and decryption.
 122          */
 123         ctx->D = ctx->E;
 124
 125         ctx->E[0] = le32_to_cpu(key[0]);
 126         ctx->E[1] = le32_to_cpu(key[1]);
 127         ctx->E[2] = le32_to_cpu(key[2]);
 128         ctx->E[3] = le32_to_cpu(key[3]);
 129
 130         /* Prepare control words. */
 131         memset(&ctx->cword, 0, sizeof(ctx->cword));
 132
 133         ctx->cword.decrypt.encdec = 1;
 134         ctx->cword.encrypt.rounds = 10 + (key_len - 16) / 4;
 135         ctx->cword.decrypt.rounds = ctx->cword.encrypt.rounds;
 136         ctx->cword.encrypt.ksize = (key_len - 16) / 8;
 137         ctx->cword.decrypt.ksize = ctx->cword.encrypt.ksize;
 138
 139         /* Don't generate extended keys if the hardware can do it. */
 140         if (aes_hw_extkey_available(key_len))
 141                 goto ok;
 142
 143         ctx->D = ctx->d_data;
 144         ctx->cword.encrypt.keygen = 1;
 145         ctx->cword.decrypt.keygen = 1;
 146
 147         if (crypto_aes_expand_key(&gen_aes, in_key, key_len)) {
 148                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 149                 return -EINVAL;
 150         }
 151
 152         memcpy(ctx->E, gen_aes.key_enc, AES_MAX_KEYLENGTH);
 153         memcpy(ctx->D, gen_aes.key_dec, AES_MAX_KEYLENGTH);
 154
 155 ok:
 156         for_each_online_cpu(cpu)
 157                 if (&ctx->cword.encrypt == per_cpu(paes_last_cword, cpu) ||
 158                     &ctx->cword.decrypt == per_cpu(paes_last_cword, cpu))
 159                         per_cpu(paes_last_cword, cpu) = NULL;
 160
 161         return 0;
 162 }
 163
 164 /* ====== Encryption/decryption routines ====== */
 165
 166 /* These are the real call to PadLock. */
 167 static inline void padlock_reset_key(struct cword *cword)
 168 {
 169         int cpu = raw_smp_processor_id();
 170
 171         if (cword != per_cpu(paes_last_cword, cpu))
 172 #ifndef CONFIG_X86_64
 173                 asm volatile ("pushfl; popfl");
 174 #else
 175                 asm volatile ("pushfq; popfq");
 176 #endif
 177 }
 178
 179 static inline void padlock_store_cword(struct cword *cword)
 180 {
 181         per_cpu(paes_last_cword, raw_smp_processor_id()) = cword;
 182 }
 183
 184 /*
 185  * While the padlock instructions don't use FP/SSE registers, they
 186  * generate a spurious DNA fault when CR0.TS is '1'.  Fortunately,
 187  * the kernel doesn't use CR0.TS.
 188  */
 189
 190 static inline void rep_xcrypt_ecb(const u8 *input, u8 *output, void *key,
 191                                   struct cword *control_word, int count)
 192 {
 193         asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
 194                       : "+S"(input), "+D"(output)
 195                       : "d"(control_word), "b"(key), "c"(count));
 196 }
 197
 198 static inline u8 *rep_xcrypt_cbc(const u8 *input, u8 *output, void *key,
 199                                  u8 *iv, struct cword *control_word, int count)
 200 {
 201         asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
 202                       : "+S" (input), "+D" (output), "+a" (iv)
 203                       : "d" (control_word), "b" (key), "c" (count));
 204         return iv;
 205 }
 206
 207 static void ecb_crypt_copy(const u8 *in, u8 *out, u32 *key,
 208                            struct cword *cword, int count)
 209 {
 210         /*
 211          * Padlock prefetches extra data so we must provide mapped input buffers.
 212          * Assume there are at least 16 bytes of stack already in use.
 213          */
 214         u8 buf[AES_BLOCK_SIZE * (MAX_ECB_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
 215         u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
 216
 217         memcpy(tmp, in, count * AES_BLOCK_SIZE);
 218         rep_xcrypt_ecb(tmp, out, key, cword, count);
 219 }
 220
 221 static u8 *cbc_crypt_copy(const u8 *in, u8 *out, u32 *key,
 222                            u8 *iv, struct cword *cword, int count)
 223 {
 224         /*
 225          * Padlock prefetches extra data so we must provide mapped input buffers.
 226          * Assume there are at least 16 bytes of stack already in use.
 227          */
 228         u8 buf[AES_BLOCK_SIZE * (MAX_CBC_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
 229         u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
 230
 231         memcpy(tmp, in, count * AES_BLOCK_SIZE);
 232         return rep_xcrypt_cbc(tmp, out, key, iv, cword, count);
 233 }
 234
 235 static inline void ecb_crypt(const u8 *in, u8 *out, u32 *key,
 236                              struct cword *cword, int count)
 237 {
 238         /* Padlock in ECB mode fetches at least ecb_fetch_bytes of data.
 239          * We could avoid some copying here but it's probably not worth it.
 240          */
 241         if (unlikely(offset_in_page(in) + ecb_fetch_bytes > PAGE_SIZE)) {
 242                 ecb_crypt_copy(in, out, key, cword, count);
 243                 return;
 244         }
 245
 246         rep_xcrypt_ecb(in, out, key, cword, count);
 247 }
 248
 249 static inline u8 *cbc_crypt(const u8 *in, u8 *out, u32 *key,
 250                             u8 *iv, struct cword *cword, int count)
 251 {
 252         /* Padlock in CBC mode fetches at least cbc_fetch_bytes of data. */
 253         if (unlikely(offset_in_page(in) + cbc_fetch_bytes > PAGE_SIZE))
 254                 return cbc_crypt_copy(in, out, key, iv, cword, count);
 255
 256         return rep_xcrypt_cbc(in, out, key, iv, cword, count);
 257 }
 258
 259 static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
 260                                       void *control_word, u32 count)
 261 {
 262         u32 initial = count & (ecb_fetch_blocks - 1);
 263
 264         if (count < ecb_fetch_blocks) {
 265                 ecb_crypt(input, output, key, control_word, count);
 266                 return;
 267         }
 268
 269         if (initial)
 270                 asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
 271                               : "+S"(input), "+D"(output)
 272                               : "d"(control_word), "b"(key), "c"(initial));
 273
 274         asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
 275                       : "+S"(input), "+D"(output)
 276                       : "d"(control_word), "b"(key), "c"(count - initial));
 277 }
 278
 279 static inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
 280                                      u8 *iv, void *control_word, u32 count)
 281 {
 282         u32 initial = count & (cbc_fetch_blocks - 1);
 283
 284         if (count < cbc_fetch_blocks)
 285                 return cbc_crypt(input, output, key, iv, control_word, count);
 286
 287         if (initial)
 288                 asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
 289                               : "+S" (input), "+D" (output), "+a" (iv)
 290                               : "d" (control_word), "b" (key), "c" (initial));
 291
 292         asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
 293                       : "+S" (input), "+D" (output), "+a" (iv)
 294                       : "d" (control_word), "b" (key), "c" (count-initial));
 295         return iv;
 296 }
 297
 298 static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 299 {
 300         struct aes_ctx *ctx = aes_ctx(tfm);
 301
 302         padlock_reset_key(&ctx->cword.encrypt);
 303         ecb_crypt(in, out, ctx->E, &ctx->cword.encrypt, 1);
 304         padlock_store_cword(&ctx->cword.encrypt);
 305 }
 306
 307 static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 308 {
 309         struct aes_ctx *ctx = aes_ctx(tfm);
 310
 311         padlock_reset_key(&ctx->cword.encrypt);
 312         ecb_crypt(in, out, ctx->D, &ctx->cword.decrypt, 1);
 313         padlock_store_cword(&ctx->cword.encrypt);
 314 }
 315
 316 static struct crypto_alg aes_alg = {
 317         .cra_name               =       "aes",
 318         .cra_driver_name        =       "aes-padlock",
 319         .cra_priority           =       PADLOCK_CRA_PRIORITY,
 320         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 321         .cra_blocksize          =       AES_BLOCK_SIZE,
 322         .cra_ctxsize            =       sizeof(struct aes_ctx),
 323         .cra_alignmask          =       PADLOCK_ALIGNMENT - 1,
 324         .cra_module             =       THIS_MODULE,
 325         .cra_u                  =       {
 326                 .cipher = {
 327                         .cia_min_keysize        =       AES_MIN_KEY_SIZE,
 328                         .cia_max_keysize        =       AES_MAX_KEY_SIZE,
 329                         .cia_setkey             =       aes_set_key,
 330                         .cia_encrypt            =       aes_encrypt,
 331                         .cia_decrypt            =       aes_decrypt,
 332                 }
 333         }
 334 };
 335
 336 static int ecb_aes_encrypt(struct blkcipher_desc *desc,
 337                            struct scatterlist *dst, struct scatterlist *src,
 338                            unsigned int nbytes)
 339 {
 340         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 341         struct blkcipher_walk walk;
 342         int err;
 343
 344         padlock_reset_key(&ctx->cword.encrypt);
 345
 346         blkcipher_walk_init(&walk, dst, src, nbytes);
 347         err = blkcipher_walk_virt(desc, &walk);
 348
 349         while ((nbytes = walk.nbytes)) {
 350                 padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
 351                                    ctx->E, &ctx->cword.encrypt,
 352                                    nbytes / AES_BLOCK_SIZE);
 353                 nbytes &= AES_BLOCK_SIZE - 1;
 354                 err = blkcipher_walk_done(desc, &walk, nbytes);
 355         }
 356
 357         padlock_store_cword(&ctx->cword.encrypt);
 358
 359         return err;
 360 }
 361
 362 static int ecb_aes_decrypt(struct blkcipher_desc *desc,
 363                            struct scatterlist *dst, struct scatterlist *src,
 364                            unsigned int nbytes)
 365 {
 366         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 367         struct blkcipher_walk walk;
 368         int err;
 369
 370         padlock_reset_key(&ctx->cword.decrypt);
 371
 372         blkcipher_walk_init(&walk, dst, src, nbytes);
 373         err = blkcipher_walk_virt(desc, &walk);
 374
 375         while ((nbytes = walk.nbytes)) {
 376                 padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
 377                                    ctx->D, &ctx->cword.decrypt,
 378                                    nbytes / AES_BLOCK_SIZE);
 379                 nbytes &= AES_BLOCK_SIZE - 1;
 380                 err = blkcipher_walk_done(desc, &walk, nbytes);
 381         }
 382
 383         padlock_store_cword(&ctx->cword.encrypt);
 384
 385         return err;
 386 }
 387
 388 static struct crypto_alg ecb_aes_alg = {
 389         .cra_name               =       "ecb(aes)",
 390         .cra_driver_name        =       "ecb-aes-padlock",
 391         .cra_priority           =       PADLOCK_COMPOSITE_PRIORITY,
 392         .cra_flags              =       CRYPTO_ALG_TYPE_BLKCIPHER,
 393         .cra_blocksize          =       AES_BLOCK_SIZE,
 394         .cra_ctxsize            =       sizeof(struct aes_ctx),
 395         .cra_alignmask          =       PADLOCK_ALIGNMENT - 1,
 396         .cra_type               =       &crypto_blkcipher_type,
 397         .cra_module             =       THIS_MODULE,
 398         .cra_u                  =       {
 399                 .blkcipher = {
 400                         .min_keysize            =       AES_MIN_KEY_SIZE,
 401                         .max_keysize            =       AES_MAX_KEY_SIZE,
 402                         .setkey                 =       aes_set_key,
 403                         .encrypt                =       ecb_aes_encrypt,
 404                         .decrypt                =       ecb_aes_decrypt,
 405                 }
 406         }
 407 };
 408
 409 static int cbc_aes_encrypt(struct blkcipher_desc *desc,
 410                            struct scatterlist *dst, struct scatterlist *src,
 411                            unsigned int nbytes)
 412 {
 413         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 414         struct blkcipher_walk walk;
 415         int err;
 416
 417         padlock_reset_key(&ctx->cword.encrypt);
 418
 419         blkcipher_walk_init(&walk, dst, src, nbytes);
 420         err = blkcipher_walk_virt(desc, &walk);
 421
 422         while ((nbytes = walk.nbytes)) {
 423                 u8 *iv = padlock_xcrypt_cbc(walk.src.virt.addr,
 424                                             walk.dst.virt.addr, ctx->E,
 425                                             walk.iv, &ctx->cword.encrypt,
 426                                             nbytes / AES_BLOCK_SIZE);
 427                 memcpy(walk.iv, iv, AES_BLOCK_SIZE);
 428                 nbytes &= AES_BLOCK_SIZE - 1;
 429                 err = blkcipher_walk_done(desc, &walk, nbytes);
 430         }
 431
 432         padlock_store_cword(&ctx->cword.decrypt);
 433
 434         return err;
 435 }
 436
 437 static int cbc_aes_decrypt(struct blkcipher_desc *desc,
 438                            struct scatterlist *dst, struct scatterlist *src,
 439                            unsigned int nbytes)
 440 {
 441         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 442         struct blkcipher_walk walk;
 443         int err;
 444
 445         padlock_reset_key(&ctx->cword.encrypt);
 446
 447         blkcipher_walk_init(&walk, dst, src, nbytes);
 448         err = blkcipher_walk_virt(desc, &walk);
 449
 450         while ((nbytes = walk.nbytes)) {
 451                 padlock_xcrypt_cbc(walk.src.virt.addr, walk.dst.virt.addr,
 452                                    ctx->D, walk.iv, &ctx->cword.decrypt,
 453                                    nbytes / AES_BLOCK_SIZE);
 454                 nbytes &= AES_BLOCK_SIZE - 1;
 455                 err = blkcipher_walk_done(desc, &walk, nbytes);
 456         }
 457
 458         padlock_store_cword(&ctx->cword.encrypt);
 459
 460         return err;
 461 }
 462
 463 static struct crypto_alg cbc_aes_alg = {
 464         .cra_name               =       "cbc(aes)",
 465         .cra_driver_name        =       "cbc-aes-padlock",
 466         .cra_priority           =       PADLOCK_COMPOSITE_PRIORITY,
 467         .cra_flags              =       CRYPTO_ALG_TYPE_BLKCIPHER,
 468         .cra_blocksize          =       AES_BLOCK_SIZE,
 469         .cra_ctxsize            =       sizeof(struct aes_ctx),
 470         .cra_alignmask          =       PADLOCK_ALIGNMENT - 1,
 471         .cra_type               =       &crypto_blkcipher_type,
 472         .cra_module             =       THIS_MODULE,
 473         .cra_u                  =       {
 474                 .blkcipher = {
 475                         .min_keysize            =       AES_MIN_KEY_SIZE,
 476                         .max_keysize            =       AES_MAX_KEY_SIZE,
 477                         .ivsize                 =       AES_BLOCK_SIZE,
 478                         .setkey                 =       aes_set_key,
 479                         .encrypt                =       cbc_aes_encrypt,
 480                         .decrypt                =       cbc_aes_decrypt,
 481                 }
 482         }
 483 };
 484
 485 static const struct x86_cpu_id padlock_cpu_id[] = {
 486         X86_FEATURE_MATCH(X86_FEATURE_XCRYPT),
 487         {}
 488 };
 489 MODULE_DEVICE_TABLE(x86cpu, padlock_cpu_id);
 490
 491 static int __init padlock_init(void)
 492 {
 493         int ret;
 494         struct cpuinfo_x86 *c = &cpu_data(0);
 495
 496         if (!x86_match_cpu(padlock_cpu_id))
 497                 return -ENODEV;
 498
 499         if (!boot_cpu_has(X86_FEATURE_XCRYPT_EN)) {
 500                 printk(KERN_NOTICE PFX "VIA PadLock detected, but not enabled. Hmm, strange...\n");
 501                 return -ENODEV;
 502         }
 503
 504         if ((ret = crypto_register_alg(&aes_alg)))
 505                 goto aes_err;
 506
 507         if ((ret = crypto_register_alg(&ecb_aes_alg)))
 508                 goto ecb_aes_err;
 509
 510         if ((ret = crypto_register_alg(&cbc_aes_alg)))
 511                 goto cbc_aes_err;
 512
 513         printk(KERN_NOTICE PFX "Using VIA PadLock ACE for AES algorithm.\n");
 514
 515         if (c->x86 == 6 && c->x86_model == 15 && c->x86_stepping == 2) {
 516                 ecb_fetch_blocks = MAX_ECB_FETCH_BLOCKS;
 517                 cbc_fetch_blocks = MAX_CBC_FETCH_BLOCKS;
 518                 printk(KERN_NOTICE PFX "VIA Nano stepping 2 detected: enabling workaround.\n");
 519         }
 520
 521 out:
 522         return ret;
 523
 524 cbc_aes_err:
 525         crypto_unregister_alg(&ecb_aes_alg);
 526 ecb_aes_err:
 527         crypto_unregister_alg(&aes_alg);
 528 aes_err:
 529         printk(KERN_ERR PFX "VIA PadLock AES initialization failed.\n");
 530         goto out;
 531 }
 532
 533 static void __exit padlock_fini(void)
 534 {
 535         crypto_unregister_alg(&cbc_aes_alg);
 536         crypto_unregister_alg(&ecb_aes_alg);
 537         crypto_unregister_alg(&aes_alg);
 538 }
 539
 540 module_init(padlock_init);
 541 module_exit(padlock_fini);
 542
 543 MODULE_DESCRIPTION("VIA PadLock AES algorithm support");
 544 MODULE_LICENSE("GPL");
 545 MODULE_AUTHOR("Michal Ludvig");
 546
 547 MODULE_ALIAS_CRYPTO("aes");